Re: Fix: Bind Cooling Device Weight

[Eduardo Valentin <edubezval@gmail.com>]

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On Thu, Dec 18, 2014 at 12:19:00PM +0000, Kapileshwar Singh wrote:
> The Problem:
> 
> In the current code, the weight of the cooling device, which is read as
> contribution from the device tree in of-thermal.c as:
> 
> 
>         ret = of_property_read_u32(np, "contribution", &prop);
>         if (ret == 0)
>                 __tbp->usage = prop;
> 
> This is only stored in the private devicedata as:
> 
>         ((__thernal_zone *)cdev->devdata)->__tbp->usage
> 
> As of-thermal.c specifies its "bind" operation and does not populate
> tzd->tzp->tbp, this causes an erroneous access in the fair-share
> governor when it tries to access the weight:
> 
> instance->target = get_target_state(tz, cdev,
>                                         tzp->tbp[i].weight,
> cur_trip_level);
> 
> 
> The Proposed solution:
> 
> The proposed solution has the following changes:
> 
>  1. Passing the weight as an argument to thermal_zone_bind_cooling_device
> 
>  2. Storing the weight in the thermal_instance data structure created in
> the thermal_zone_bind_cooling_device function
> 
>  3. Changing the accesses in the governor accordingly.

Shouldn't we simply:
1. In of-thermal, populate tzd->tzp->tbp by passing a tbp with correct
tbp's in the registration call:
	zone = thermal_zone_device_register(child->name, tz->ntrips,
						0,
						tz,
						ops,
/* This guy needs to be filled properly */	tzp,
						tz->passive_delay,
						tz->polling_delay);

2. Add a proper check in the governor to avoid accessing thermal zones
with missing data.

I know there is a check in place:
        if (!tz->tzp || !tz->tzp->tbp)
	          return -EINVAL;

which based in your description seams to be failing. Here, I need more
info from your side describing what exactly you are seeing. Can you
please post the kernel log when the failure happens? Does it output a
kernel segfault or is the governor simply not working?

I would expect, with the current code, the governor be silent and
non-functional, which needs to be fixed too.
> 
>  I am not sure of what default value should be assigned to the weight
> member in the instance data structure and would like to leave this open
> to discussion.
> 
> Suggested Patch (Not Signed off):
> 
> diff --git a/drivers/thermal/db8500_thermal.c
> b/drivers/thermal/db8500_thermal.c
> index 1e3b3bf9f993..e3ccc2218eb3 100644
> --- a/drivers/thermal/db8500_thermal.c
> +++ b/drivers/thermal/db8500_thermal.c
> @@ -76,7 +76,7 @@ static int db8500_cdev_bind(struct thermal_zone_device
> *thermal,
>          upper = lower = i > max_state ? max_state : i;
>  
>          ret = thermal_zone_bind_cooling_device(thermal, i, cdev,
> -            upper, lower);
> +            upper, lower, THERMAL_WEIGHT_DEFAULT);
>  

I think spreading such parameter, which is known to be part of tbp, is
not a good thing to do. Can we avoid that?


Cheers, Eduardo
>          dev_info(&cdev->device, "%s bind to %d: %d-%s\n", cdev->type,
>              i, ret, ret ? "fail" : "succeed");
> diff --git a/drivers/thermal/fair_share.c b/drivers/thermal/fair_share.c
> index 6e0a3fbfae86..c3b25187b467 100644
> --- a/drivers/thermal/fair_share.c
> +++ b/drivers/thermal/fair_share.c
> @@ -109,7 +109,7 @@ static int fair_share_throttle(struct
> thermal_zone_device *tz, int trip)
>              continue;
>  
>          instance->target = get_target_state(tz, cdev,
> -                    tzp->tbp[i].weight, cur_trip_level);
> +                    instance->weight, cur_trip_level);
>  
>          instance->cdev->updated = false;
>          thermal_cdev_update(cdev);
> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> index 5a1f1070b702..74d0c9951eef 100644
> --- a/drivers/thermal/imx_thermal.c
> +++ b/drivers/thermal/imx_thermal.c
> @@ -307,7 +307,8 @@ static int imx_bind(struct thermal_zone_device *tz,
>  
>      ret = thermal_zone_bind_cooling_device(tz, IMX_TRIP_PASSIVE, cdev,
>                             THERMAL_NO_LIMIT,
> -                           THERMAL_NO_LIMIT);
> +                           THERMAL_NO_LIMIT
> +                           THERMAL_WEIGHT_DEFAULT);
>      if (ret) {
>          dev_err(&tz->device,
>              "binding zone %s with cdev %s failed:%d\n",
> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
> index e032b9bf4085..cf4036cbb671 100644
> --- a/drivers/thermal/of-thermal.c
> +++ b/drivers/thermal/of-thermal.c
> @@ -157,7 +157,8 @@ static int of_thermal_bind(struct
> thermal_zone_device *thermal,
>              ret = thermal_zone_bind_cooling_device(thermal,
>                          tbp->trip_id, cdev,
>                          tbp->max,
> -                        tbp->min);
> +                        tbp->min,
> +                        tbp->usage);
>              if (ret)
>                  return ret;
>          }
> diff --git a/drivers/thermal/samsung/exynos_thermal_common.c
> b/drivers/thermal/samsung/exynos_thermal_common.c
> index b6be572704a4..d653798b519f 100644
> --- a/drivers/thermal/samsung/exynos_thermal_common.c
> +++ b/drivers/thermal/samsung/exynos_thermal_common.c
> @@ -163,7 +163,7 @@ static int exynos_bind(struct thermal_zone_device
> *thermal,
>          case MONITOR_ZONE:
>          case WARN_ZONE:
>              if (thermal_zone_bind_cooling_device(thermal, i, cdev,
> -                                level, 0)) {
> +                                level, 0, THERMAL_WEIGHT_DEFAULT)) {
>                  dev_err(data->dev,
>                      "error unbinding cdev inst=%d\n", i);
>                  ret = -EINVAL;
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 4921e084c20b..199866864ef1 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -277,7 +277,8 @@ static void print_bind_err_msg(struct
> thermal_zone_device *tz,
>  
>  static void __bind(struct thermal_zone_device *tz, int mask,
>              struct thermal_cooling_device *cdev,
> -            unsigned long *limits)
> +            unsigned long *limits,
> +            unsigned int weight)
>  {
>      int i, ret;
>  
> @@ -292,7 +293,8 @@ static void __bind(struct thermal_zone_device *tz,
> int mask,
>                  upper = limits[i * 2 + 1];
>              }
>              ret = thermal_zone_bind_cooling_device(tz, i, cdev,
> -                                   upper, lower);
> +                                   upper, lower,
> +                                   weight);
>              if (ret)
>                  print_bind_err_msg(tz, cdev, ret);
>          }
> @@ -339,7 +341,8 @@ static void bind_cdev(struct thermal_cooling_device
> *cdev)
>                  continue;
>              tzp->tbp[i].cdev = cdev;
>              __bind(pos, tzp->tbp[i].trip_mask, cdev,
> -                   tzp->tbp[i].binding_limits);
> +                   tzp->tbp[i].binding_limits,
> +                   tzp->tbp[i].weight);
>          }
>      }
>  
> @@ -378,7 +381,8 @@ static void bind_tz(struct thermal_zone_device *tz)
>                  continue;
>              tzp->tbp[i].cdev = pos;
>              __bind(tz, tzp->tbp[i].trip_mask, pos,
> -                   tzp->tbp[i].binding_limits);
> +                   tzp->tbp[i].binding_limits,
> +                   tzp->tbp[i].weight);
>          }
>      }
>  exit:
> @@ -770,7 +774,8 @@ passive_store(struct device *dev, struct
> device_attribute *attr,
>                  thermal_zone_bind_cooling_device(tz,
>                          THERMAL_TRIPS_NONE, cdev,
>                          THERMAL_NO_LIMIT,
> -                        THERMAL_NO_LIMIT);
> +                        THERMAL_NO_LIMIT,
> +                        THERMAL_WEIGHT_DEFAULT);
>          }
>          mutex_unlock(&thermal_list_lock);
>          if (!tz->passive_delay)
> @@ -1009,7 +1014,9 @@ thermal_cooling_device_trip_point_show(struct
> device *dev,
>   * @lower:    the Minimum cooling state can be used for this trip point.
>   *        THERMAL_NO_LIMIT means no lower limit,
>   *        and the cooling device can be in cooling state 0.
> - *
> + * @weight:    The weight of the cooling device to be bound to the
> +        thermal zone. THERMAL_WEIGHT_DEFAULT for default value
> +
>   * This interface function bind a thermal cooling device to the certain
> trip
>   * point of a thermal zone device.
>   * This function is usually called in the thermal zone device .bind
> callback.
> @@ -1019,7 +1026,8 @@ thermal_cooling_device_trip_point_show(struct
> device *dev,
>  int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
>                       int trip,
>                       struct thermal_cooling_device *cdev,
> -                     unsigned long upper, unsigned long lower)
> +                     unsigned long upper, unsigned long lower,
> +                     unsigned int weight)
>  {
>      struct thermal_instance *dev;
>      struct thermal_instance *pos;
> @@ -1062,6 +1070,7 @@ int thermal_zone_bind_cooling_device(struct
> thermal_zone_device *tz,
>      dev->upper = upper;
>      dev->lower = lower;
>      dev->target = THERMAL_NO_TARGET;
> +    dev->weight = weight;
>  
>      result = get_idr(&tz->idr, &tz->lock, &dev->id);
>      if (result)
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index b907be823527..1c61abe7801f 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
> @@ -48,6 +48,7 @@ struct thermal_instance {
>      struct device_attribute attr;
>      struct list_head tz_node; /* node in tz->thermal_instances */
>      struct list_head cdev_node; /* node in cdev->thermal_instances */
> +    unsigned int weight; /* The weight of the cooling device */
>  };
>  
>  int thermal_register_governor(struct thermal_governor *);
> diff --git a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> index 9eec26dc0448..772549ec9bd8 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> @@ -147,7 +147,8 @@ static int ti_thermal_bind(struct
> thermal_zone_device *thermal,
>      return thermal_zone_bind_cooling_device(thermal, 0, cdev,
>      /* bind with min and max states defined by cpu_cooling */
>                          THERMAL_NO_LIMIT,
> -                        THERMAL_NO_LIMIT);
> +                        THERMAL_NO_LIMIT,
> +                        THERMAL_WEIGHT_DEFAULT);
>  }
>  
>  /* Unbind callback functions for thermal zone */
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index fc4fdcbbdecc..674795ba0900 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -40,6 +40,9 @@
>  /* No upper/lower limit requirement */
>  #define THERMAL_NO_LIMIT    ((u32)~0)
>  
> +/* Default weight of a bound cooling device */
> +#define THERMAL_WEIGHT_DEFAULT 1
> +
>  /* Unit conversion macros */
>  #define KELVIN_TO_CELSIUS(t)    (long)(((long)t-2732 >= 0) ?    \
>                  ((long)t-2732+5)/10 : ((long)t-2732-5)/10)
> @@ -375,7 +378,8 @@ void thermal_zone_device_unregister(struct
> thermal_zone_device *);
>  
>  int thermal_zone_bind_cooling_device(struct thermal_zone_device *, int,
>                       struct thermal_cooling_device *,
> -                     unsigned long, unsigned long);
> +                     unsigned long, unsigned long,
> +                     unsigned int);
>  int thermal_zone_unbind_cooling_device(struct thermal_zone_device *, int,
>                         struct thermal_cooling_device *);
>  void thermal_zone_device_update(struct thermal_zone_device *);
> 
> 

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